These regex changes fix a number of issues for distutils on Windows: - #6884: impossible to include a file starting with 'build' - #9691 and #14004: sdist includes too many files - #13193: test_filelist failures This commit replaces the incorrect changes done in 0a94e2f807c7 and 90b30d62caf2 to fix #13193; we were too eager to fix the test failures and I did not study the code enough before greenlighting patches. This time we have unit tests from the problems reported by users to be sure we have the right fix. Thanks to Nadeem Vawda for his help.